Arc lamp with air current concentration



June 23, 1959 GRETENER 2,892,118

ARC LAMP WITH AIR CURRENT CONCENTRATION Filed Dec. 30, 1955 INVENTOR Edgar Grefener ATTORNEYS United States Patent ARC LAMP WITH AIR CURRENT CONCENTRATION Edgar Gretener, Zurich, Switzerland, assignor to Edgar Gretener A.G., Zurich, Switzerland Application December 30, 1955, Serial No. 556,660

Claims priority, application Switzerland December 30, 1954 1 Claim. (Cl. 313-449) The present invention is related to an arc lamp with air current concentration.

Lamps of this kind are well known. A blower nozzle is located at the positive head of the lamp which directs air from the rear towards the front end of the positive carbon. This air stream concentrically surrounds the arcing end and contracts in form of a cone. Thereby arc discharge and anode flame are concentrated into the space in front of the positive crater and form an intensely radiating cylinder. The air current carries away evaporation and oxidation products from the positive carbon and is received by an exhaust tube at the rear of the negative carbon which it surrounds coaxially.

If such a lamp is operated with high current load and short gap, disturbances of operation may be caused by evaporation products depositing on the tip of the negative carbon. Mostly there are difliculty oxidizable carbides, so that normal burning of the carbons is prevented and a correct functioning of the lamp is made impossible.

The object of the present invention is to remedy these defects. It is directed to an arc lamp with air current concentration and is characterized by a rod shaped negative carbon which is rotated around its axis during operation, said axis being inclined towards the rod shaped positive carbon and the tip of which does not reach up to the axis of the positive carbon, so that the arc discharge on the negative carbon is located eccentrically and that the arcing spot is continuously led away from the are by rotation and gets into contact with exterior parts of the air stream.

The invention will be explained in the following with the aid of an embodiment shown in the attached drawing the single figure of which schematically represents a side view of an arc lamp according to the invention.

The positive carbon 1 is surrounded by the blower nozzle 2, from the front openings 3 of which a concentric air stream is directed towards the arcing end 4 of carbon 1. The air current contracts conically and concentrates the arc discharge 6 between the positive carbon and the negative carbon 7 into an intensely luminous cylinder. The air stream is received by an exhaust funnel 8, which is located at the rear of tip 9 of the negative carbon. Positive carbon 1 and negative carbon 7 are fed forward in the well known manner by transport rolls 10 and 11 to make up for consumption during operation.

According to the invention the negative carbon 7 is rotated around its axis during operation. This by way of example may be effected by the particular form of the transport rolls 11 shown in the drawing. They urge carbon 7 against guide 13 by means of springs 12, said 2,892,118 Patented June 23, 1959 guide serving at the same time for current connection. Rolls 11 have a thread cut in additionally to the axial knurling. Thereby rolls 11 at the same time rotate and feed forward the negative carbon.

According to the invention furthermore the negative carbon is so disposed that its axis 15 is inclined to the axis 14 of the positive carbon 1 and that its tip 9 does not reach up to the axis of the positive carbon. Tip 9 of the negative carbon thus is located eccentrically with respect to the axis of the positive carbon. As a consequence the arcing spot 16 of the discharge, which is the point on which the arc discharge sits upon the negative carbon is located eccentrically with respect to the axis 15 of the negative carbon. Due to the rotation the arcing spot, which is that part of the surface of the negative carbon where the arc sits upon, is continuously moved out of the arc discharge and gets into contact with the exterior parts of the air stream. If, as mentioned above, evaporation products from the positive carbon have deposited on the arcing spot they get into contact with parts of the air stream rich in oxygen and are oxidized as they are still heated by the arc discharge. No stable deposits may consequently form.

This oxidation of evaporation products cannot be effected if the carbon is not rotated as at the center of the arc discharge oxygen is missing. Only by rotation of the negative carbon it is possible to transport the deposited evaporation products into parts of the are which are rich in oxygen and thus remove them from the carbon by oxidation. This is effected according to the invention by a particular choice of the relative position of negative carbon and positive carbon in such a manner that the arcing spot of the are on the negative carbon is located eccentrically to its axis of rotation and will consequently be continuously carried out of the are discharge.

I claim:

In an arc lamp with air concentration, a positive rodshaped carbon, a negative rod-shaped carbon, a blower nozzle arranged concentrically around said positive carbon and directing an air stream concentrically converging and surrounding the tip of the positive carbon, means for rotating said negative carbon around its axis, the negative carbon having its axis inclined to the axis of the positive carbon and having its tip so located that it does not reach the axis of the positive carbon, and having its tip furthermore located eccentrically with respect to said air stream that the one side of the tip is located next to the center part of the air stream and the other side thereof next to the exterior parts of the air stream, whereby the are ends on a spot eccentrically located on the tip of the negative carbon, and whereby matter from the positive carbon deposited by the are on said spot on the tip of the negative carbon is continuously carried out of the are into the exterior parts of the air stream.

References Cited in the file of this patent UNITED STATES PATENTS 493,359 Hunter Mar. 14, 1893 1,632,131 Hall June 14, 1927 1,671,805 Bassett May 29, 1928 2,724,787 Gretener Nov. 22, 1955 2,732,515 Millie et a1. Ian. 24, 1956 2,788,459 Gretener Apr. 9, 1957 

